Macroscopic domain formation during cooling in the platelet plasma membrane: An issue of low cholesterol content

Rachna Bali, Laura Savino, Diego A. Ramirez, Nelly M. Tsvetkova, Luis Bagatolli, Fern Tablin, John H. Crowe, Chad Leidy

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

There has been ample debate on whether cell membranes can present macroscopic lipid domains as predicted by three-component phase diagrams obtained by fluorescence microscopy. Several groups have argued that membrane proteins and interactions with the cytoskeleton inhibit the formation of large domains. In contrast, some polarizable cells do show large regions with qualitative differences in lipid fluidity. It is important to ask more precisely, based on the current phase diagrams, under what conditions would large domains be expected to form in cells. In this work we study the thermotropic phase behavior of the platelet plasma membrane by FTIR, and compare it to a POPC/Sphingomyelin/Cholesterol model representing the outer leaflet composition. We find that this model closely reflects the platelet phase behavior. Previous work has shown that the platelet plasma membrane presents inhomogeneous distribution of DiI18:0 at 24 °C, but not at 37 °C, which suggests the formation of macroscopic lipid domains at low temperatures. We show by fluorescence microscopy, and by comparison with published phase diagrams, that the outer leaflet model system enters the macroscopic domain region only at the lower temperature. In addition, the low cholesterol content in platelets (∼ 15 mol%), appears to be crucial for the formation of large domains during cooling.

Original languageEnglish (US)
Pages (from-to)1229-1237
Number of pages9
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1788
Issue number6
DOIs
StatePublished - Jun 2009

Keywords

  • Cholesterol
  • FTIR
  • Lipid domain formation
  • Lipid membrane thermodynamics
  • Lipid platform
  • Lipid raft
  • Liquid-ordered phase
  • Platelet

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Biophysics

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